Additive and inkjet recording medium using additives

ABSTRACT

An additive which can improve the water resistance of a water-soluble dye with which an article has been dyed; and an ink-jet recording medium which contains the additive, is exellent in the water resistance and resolution of characters or images recorded thereon, and is suitable for multicolor recordeng. The additive is obtained by reacting a secondary amine, ammonia, an epihalohydrin, and a crosslinking agent as essential ingredients. The recording medium is obtained by causing the additive to be present on a surface and/or inner part of a base.

FIELD OF THE INVENTION

This invention relates to an additive having a cationic resin which canrender a water-soluble dye water resistant as principal component, andto an inkjet recording medium comprising this additive in the surfaceand/or interior of a substrate.

BACKGROUND OF THE INVENTION

In inkjet recording, a coloured dye or coloured pigment dispersed, in anaqueous or non-aqueous solvent, is extruded as minute fine drops fromone or more nozzles, and the liquid drops are made to form a desiredcharacter or image by electronic control on the recording medium.

As a recording medium employing this recording method, paper used forelectrostatic transfer or ordinary paper used for writing can be used,but to obtain a good recorded image, the recording medium must have thefollowing two sets of characteristics. The first set of characteristicsis good ink absorption, ink drops adhering to the surface of the mediumrapidly penetrate the interior of the medium, the image rapidly developsa dry appearance, and the image does not smudge on contact with therecording device, another medium or the hands. The second set ofcharacteristics is that ink drops do not diffuse through the interior orsurface of the medium more than is necessary, and dots recorded by theink drops do not become too large or assume a distorted shape.

The coloured components used in the ink may be direct dyes, acidic dyes,basic dyes, reactive dyes, dispersion dyes or various pigments.Water-soluble dyes are most often used, but in the case of inkjetrecording, there is usually a very serious problem insofar as therecorded image has poor water resistance. For example, when an imagerecorded by the inkjet recording method is taken outdoors, it may occurthat of the image smudges due to rain and the recorded image can nolonger be read. Alternatively, if the image is left for a long period oftime under high humidity conditions, it may smudge and spoil the imagequality.

Hence, to make the recorded image from inkjet recording water resistant,in Tokkai Sho 55-150396 (Koho), an invention is proposed wherein, afterprinting is performed using a water-based dye ink, a reagent is usedwhich forms a lake with the dye to confer water resistance.

Various compounds that are ink water resistance-conferring agents andwhich can be first added to the ink-receiving layer of the inkjetrecording medium, are also known. For example, JP,56-59239. (Koho)proposes a polycation polyelectrolyte, JP,61-68788 (Koho) proposes aweak acid salt of a polyallylamine, JP,60-49990 (Koho) proposes anammonium polyalkylene polyamine dicyandiamide, JP,1-157884 (Koho)proposes chitosan, JP,6-92011 (Koho) proposes cation denaturationcolloidal silica, while JP,6-92012 (Koho) proposes a copolymer ofdimethylamine and epichlorohydrin, these compounds being added to theink-receiving layer beforehand.

Besides the above-mentioned compounds, cationic resins such asdicyandiamide formaldehyde resin, diethylenetriamine dicyandiamideammonium chloride condensate, (meta)acryloyloxy-alkyl trialkylammoniumchloride polymer, dimethyl diallylammonium chloride polymer,ethyleneimine polymers, diallylamine polymers andammonia/epichlorohydrin/dimethylamine copolymers, are already known asan ink water resistance-conferring agents.

It is known that the aforementioned water-soluble cationic resins formcomplexes by bonding to anionic water-soluble direct dyes, acidic dyes,reactive dye, etc., thereby increasing the water resistance ofwater-soluble paints and preventing decoloring of yarn, cloth, etc. dyedwith water-soluble paints.

However, if a solvent such as water is present in the environment when acomplex with a dye molecule is made, the complex will displace easilyfrom the dyed object, so these water-soluble cationic resins apparentlyhave a low waterproofing effectiveness, and even if they were used as anink jet recording medium, they did not give satisfactory recordingquality.

It is therefore a first object of this invention to provide an additivehaving a cationic resin as its principal component which has a largeeffectiveness in improving the waterproof properties of an image coloredor recorded with a water soluble dye. It is a second object of thisinvention to provide a recorded medium suitable for multicolor recordingby the ink-jet recording method which not only addresses the problem ofinadequate waterproofness of recorded characters and images, which wasthe defect of conventional inkjet recording media, but also improvesresolution and color tone, provides a high resolution similar to that ofa silver salt photograph, and gives little difference of hue of recordedcharacters or images compared to the hue of the dyes themselves whichare currently used in ink.

DISCLOSURE OF THE INVENTION

This invention relates to an additive having a cationic resin asprincipal component, the resin being obtained by reaction of at least asecondary amine, ammonia, epichlorohydrin and a crosslinking agent, andto an ink-jet recording medium comprising this additive in the surfaceand/or interior of a substrate. The additive of this invention partlycomprises a cationic resin having a crosslinked structure as principalcomponent, hence even if a solvent such as water is present in theenvironment, a complex with a dye molecule cannot easily be displacedfrom a dyed object, and the durability of the image can be largelyimproved. The additive of this invention not only is effective inimproving the durability of a water-based ink image, but also improvesthe resolution and color tone of the image. Therefore, by incorporatingthe additive having the cationic resin as principal component in thesurface and/or interior of a substrate of a recording medium, an inkjetrecording medium is obtained which not only has excellent waterproofnessand gives little blurring of dots, but also has an identical coloringhue to that of the dye itself, and allows a high resolution, highquality image to be obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The cationic resin of this invention has a secondary amine, ammonia, anepihalohydrin-compound and a crosslinking agent as required components,and can be obtained by their reaction. These components can be usedindependently, or a mixture of two or more of them may be used together.

The secondary amine used in this invention may be an aliphatic secondaryamine, aromatic secondary amine or cyclic secondary amine, but analiphatic secondary amine is to be preferred. Examples of aliphaticsecondary amines are dimethylamine, diethylamine, dipropylamine,dibenzylamine, ethyl monomethylamine, methyl propylamine,butylmonomethylamine, methyl octylamine and methyl laurylamine. Of thesedialkylamines, dimethylamine, diethylamine and ethyl monomethylamine areparticularly desirable.

The ammonia used in this invention may be any of liquid ammonia, ammoniagas and aqueous ammonia solution, there being no particular limitationon the concentration of aqueous ammonia solution.

The epihalohydrin compound used in this invention may beepichlorohydrin, epiiodohydrin or epibromohydrin, epichlorohydrin beingparticularly preferred.

The crosslinking agent used in this invention may be any compound withtwo or more crosslinking functional groups such as aldehyde groups,epoxy groups and isocyanate groups, but compounds containing epoxygroups are to be preferred. Suitable examples are multifunctional epoxycompounds such as polyethylene glycol diglycidyl ether, polypropyleneglycol diglycidyl ether, polytetramethylene glycol diglycidyl ether,polybutadiene diglycidyl ether, resorcinol diglycidyl ether,neopentylglycol diglycidyl ether, 1,6-hexanediol diglycidyl ether,bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol Apolyethylene glycol diglycidyl ether, bisphenol A polypropyleneglycoldiglycidyl ether, hydrated bisphenol A diglycidyl ether, hydroquinonediglycidyl ether, terephthalic acid diglycidyl ether, sorbitolpolyglycidyl ether, polyglycerol polyglycidyl ether,pentaerythritolpolyglycidyl ether, diglyceroylpolyglycidyl ether,glycerolpolyglycidyl ether, and trimethylolpropane polyglycidyl ether.,

In the method of synthesizing the cationic resin, in JP,10-152544(Koho), the order in which ammonia, amines and epihalohydrins may bemade to react is disclosed. However, in the synthesis of the cationicresin of this invention, the epihalohydrin compound is gradually drippedin after first mixing the secondary amine and ammonia together in areaction solvent, and the crosslinking agent is then added gradually. Ifthe crosslinking agent and the secondary amine or ammonia are reactedtogether first, the reaction becomes uneven, and the target compound isnot obtained.

In a preferred method of synthesizing the cationic resin of thisinvention, the secondary amine and ammonia are dissolved undertemperature less than ordinal temperature in water or an organicsolvent, for example, methanol, ethanol, 2-propanol, butanol, ethyleneglycol, dioxane, dimethylformamide, 2-ethoxyethanol or dimethylsulfoxide, the epihalohydrin is dripped in, the temperature of thereaction mixture is raised to 30-100° C., the crosslinking agent isadded, and the reaction is performed for 10-20 hours.

A desirable mole ratio of monomer components in the cationic resin ofthis invention obtained by reaction of secondary amine, ammonia,epihalohydrin compound and crosslinking agent (secondary amine: ammonia:epihalohydrin compound: cross linking agent) is 1:(0.01-2):(0.5-2.5):(0.00005-0.05), and prefer-ably 1:(0.02-1):(0.8-2.2): (0.0001-0.01).

If the epihalohydrin compound is less than 0.5 mols, the secondary amineand ammonia cannot fully react with the epihalohydrin, so even if thecompound obtained is used as a recording medium, it is difficult toobtain an ink jet recording target giving excellent water resistance ofthe recorded image. If the epihalohydrin compound is increased to exceed2.5 mols, the resin obtained is difficultly soluble or insoluble inwater, so it is unsuitable for manufacture of a recording medium in anaqueous system, and must be manufactured in a solvent system.

Alternatively, if the crosslinking agent is increased so that 0.05 molsare exceeded, although the reason is not clear, the desired compoundcannot be obtained and it is difficult to use for manufacture of therecording medium of this invention. Conversely, if the crosslinkingagent is reduced to less than 0.00005 mols, a good inkjet recordingmedium having good image water resistance cannot be manufactured.

The average molecular weight of the cationic resin of this invention ispreferably 10,000-500,000, and more preferably 50,000-250,000 as aweighted mean. The reactivity with dye molecules falls if the weightaverage molecular weight is larger than 500,000, and the waterresistance of the record image cannot be increased. Conversely, if theweight average molecular weight is less than 10,000, the reactivity withdye molecules increases too much, so when the resin comes in contactwith ink, it reacts rapidly with the dye molecules in the ink to producea precipitate, and in this case, the ink absorptivity of the recordingmedium falls.

Although the cationic resin of this invention is thought to be generatedby the copolymerization of a secondary amine, ammonia, epihalohydrincompounds and a crosslinking agent, the molecular structure of thiscationic resin has not yet been elucidated by the Inventor and others.

The state of the reaction system in the synthetic end phase of thiscationic resin is solution-like or colloid-like, and the pH is 4-9. Thecolor is light yellow, yellow, yellow brown, dark reddish-brown orbrown.

The additive having the cationic resin of this invention as principalcomponent (referred to hereafter simply as additive) may be the solutionobtained when the synthesis of the cationic resin composition of thisinvention is complete, or alternatively it may be used in the colloidstate as it is. The solvent or unreacted monomer may of course also beremoved. Moreover, reagents such as a stabilizing agent or antisepticcan be added to the additive of this invention to the extent that theydo not spoil the effectiveness of this invention.

As the substrate of the ink jet recording medium used in this invention,although paper is typical, cloth, nonwoven fabric, resin sheet, film,synthetic paper or metal sheet, etc. can be suitably chosen from themedia on which ink jet recording is possible.

The ink jet recording medium containing the additive of this inventionmay be manufactured by immersing a substrate in an impregnating liquidcontaining the additive of this invention, then drying, or incorporatingthe additive of this invention in a coating liquid, applying the coatingliquid to the substrate and drying so as to form a layer containing theadditive of this invention on the surface of the recording medium; orwhen the substrate is paper, by mixing the additive with pulp and otheringredients in a substrate manufacturing step in the manufacture ofpaper, and these methods can also be combined. These methods may furtherbe combined with known methods such as the impregnation method, coatingmethod and internal addition method as appropriate.

The aforesaid impregnation liquid or coating liquid may contain furtheradditives which are generally used, such as a filler or a binder, apigment, a water retention agent, a water resistant agent, an opticalwhitening agent, pH regulator, defoaming agent, lubricant, antiseptic,surfactant or electrical conduction agent.

The drying method may be any of the usual methods, such as a steamheater, gas heater, infrared heater, electric heater, hot blast heater,microwave or cylindrical dryer. After drying, the product can be given agloss if necessary by finishers such as a supercalender which is postprocessing, and a soft calender etc, which are finishing processing. Inaddition, it is also possible to perform general machining as may beconvenient.

The ink jet recording medium obtained as described above may contain anarbitrary amount of the additive of this invention, the range of 0.1-25g/m² being especially desirable. If the amount is less than 0.1 g/m²,water resistance is inadequate when the medium is used in an inkjetrecording device having a high ink discharge amount, and when the amountis higher than 25 g/m², the hue of the original dye and the hue of therecorded image shift so that image quality deteriorates.

The water-based ink used for ink jet recording normally comprises awater-soluble direct dye, acid dye, base dye or reactive dye as coloranttogether with water, lower alcohols or alkyl ethers of same as solvent.The lower alcohols are preferably polyhydric alcohols such as ethyleneglycol, diethylene glycol, triethylene glycol or glycerol, and theiralkyl ethers, and alkyl ethers of same are preferably low alkyl etherssuch as diethylene glycol monomethylether, diethylene glycol monoethylether and triethylene glycol monomethyl ether. Other ink additives arefor example antifungal agents, germicides, antioxidants, pH regulators,dispersants, rust preventives, chelating agents, surfactants orviscosity regulators, etc.

When the additive of this invention is used in an ink jet recordingmedium, anions of a dye molecule which is the coloring component in inkinteracts with the additive of the invention so that a water-soluble dyebecomes insoluble or difficultly soluble in water. As a result, an imagerecorded with high resolution as a picture or a character on therecording medium becomes water-resistant, does not smudge, and anexcellent image with a small variation of hue is obtained.

Although the mechanism of the above interaction is not clear, thecationic resin obtained by copolymerization of the secondary amine,ammonia, epihalohydrin compound and crosslinking agent may form aproperly developed network structure. After the reaction, this mixeswith the solvent, but it is thought that after drying it becomesinsoluble in water, and therefore has a far superior effect to that ofthe cationic resins of the prior art.

The additive of this invention can also prevent decoloring of yarn andcloth which were dyed using a water-soluble dye, and this is consideredto be due to the above-mentioned reason.

EXAMPLES

Hereafter, this invention is further explained in detail by way ofexamples, but this invention is not limited to these. “Parts” and “%”refer to weight parts and wt % unless otherwise stated.

Synthesis Example 1

202.9 g dimethylamine (50%), 17.6 g of 0.24 wt % aqueous ammonia and 310g water were introduced into a reaction vessel equipped with a stirrer,reflux condenser, dropping funnel and thermometer, and after stirring todissolve the ingredients to obtain a homogeneous mixture, 238.6 g of anepichlorohydrin compound was dripped in using the dropping funnel. Afteraddition was complete, the mixture was reacted at 70° C. for 15 hours.Next, 0.3 g bisphenol A propoxylate (1 propylene oxide/phenol)diglycidyl ether was added from the dropping funnel, and reacted at 90°C. for 5 hours to obtain a yellow liquefied aqueous solution containing45% solids. The weight average molecular weight of the polymer obtainedas found by high performance liquid chromatography was approximately18,000. This will be referred to as Additive 1.

Synthesis Example 2

202.9 g dimethylamine (50%), 17.6 g of 24 wt % aqueous ammonia and 310 gwater were introduced into a reaction vessel equipped with a stirrer,reflux condenser, dropping funnel and thermometer, and after stirring todissolve the ingredients to obtain a homogeneous mixture, 238.6 g of anepichlorohydrin compound was dripped in using the dropping funnel. Afteraddition was complete, the mixture was reacted at 70° C. for 15 hours.Next, 0.2 g neopentyl glycol diglycidyl ether was added from thedropping funnel, and reacted at 90° C. for 5 hours to obtain a lightyellow aqueous solution containing 45% solids. The weight averagemolecular weight of the polymer obtained as found by high performanceliquid chromatography was approximately 18,000. This will be referred toas Additive 2.

Synthesis Example 3

202.9 g dimethylamine (50%), 17.6 g of 24 wt % aqueous ammonia and 310 gwater were introduced into a reaction vessel equipped with a stirrer,reflux condenser, dropping funnel and thermometer, and after stirring todissolve the ingredients to obtain a homogeneous mixture, 238.6 g ofepichlorohydrin was dripped in using the dropping funnel. After additionwas complete, the mixture was reacted at 70° C. for 15 hours. Next, 0.2g 1,6-hexanediol diglycidyl ether was added from the dropping funnel,and reacted at 90° C. for 5 hours to obtain a light yellow aqueoussolution containing 45% solids. The weight average molecular weight ofthe polymer obtained as found by high performance liquid chromatographywas approximately 18,000. This will be referred to as Additive 3.

Synthesis Example 4

202.9 g dimethylamine (50%), 17.6 g of 24 wt % aqueous ammonia and 310 gwater were introduced into a reaction vessel equipped with a stirrer,reflux condenser, dropping funnel and thermometer, and after stirring todissolve the ingredients to obtain a homogeneous mixture, 238.6 g ofepichlorohydrin was dripped in using the dropping funnel. After additionwas complete, the mixture was reacted at 70° C. for 15 hours. Next, 0.3g hydrated bisphenol A diglycidyl ether was added from the droppingfunnel, and reacted at 90° C. for 5 hours to obtain a light yellowaqueous solution containing 45% solids. The weight average molecularweight of the polymer obtained as found by high performance liquidchromatography was approximately 18,000. This will be referred to asAdditive 4.

Synthesis Example 5

273.9 g ethylamine (50%), 17.5 g of 25 wt % aqueous ammonia and 314.4 gwater were introduced into a reaction vessel equipped with a stirrer,reflux condenser, dropping funnel and thermometer, and after stirring todissolve the ingredients to obtain a homogeneous mixture, 238.6 g ofepichlorohydrin was dripped in using the dropping funnel. After additionwas complete, the mixture was reacted at 80° C. for 15 hours. Next, 1.0g bisphenol A propoxylate (1-propylene oxide/phenol) diglycidyl etherwas added from the dropping funnel, and reacted at 90° C. for 5 hours toobtain a yellow liquefied aqueous solution containing 45% solids. Theweight average molecular weight of the polymer obtained as found by highperformance liquid chromatography was approximately 30,000. This will bereferred to as Additive 5.

Synthesis Example 6

150.6 g dimethylamine (50%), 35.1 g of 20 wt % aqueous ammonia and 460.1g water were introduced into a reaction vessel equipped with a stirrer,reflux condenser, dropping funnel and thermometer, and after stirring todissolve the ingredients to obtain a homogeneous mixture, 238.6 g ofepichlorohydrin was dripped in using the dropping funnel. After additionwas complete, the mixture was reacted at 909 for 15 hours. Next, 1.0 gbisphenol A propoxylate (1-proplyene oxide/phenol) diglycidyl ether wasadded from the dropping funnel, and reacted at 90° C. for 5 hours toobtain a yellow liquefied aqueous solution containing 45% solids. Theweight average molecular weight of the polymer obtained as found by highperformance liquid chromatography was approximately 40,000. This will bereferred to as Additive 6.

Synthesis Example 7

185.7 g dimethylamine (50%), 35.1 g of 25 wt % aqueous ammonia and 391.3g water were introduced into a reaction vessel equipped with a stirrer,reflux condenser, dropping funnel and thermometer, and after stirring todissolve the ingredients to obtain a homogeneous mixture, 238.6 g ofepichlorohydrin was dripped in using the dropping funnel. After additionwas complete, the mixture was reacted at 70° C. for 15 hours. Next, 1.0g hydrated bisphenol A diglycidyl ether was added from the droppingfunnel, and reacted at 60° C. for 7 hours to obtain a yellow liquefiedaqueous solution containing 40% solids. The weight average molecularweight of the polymer obtained as found by high performance liquidchromatography was approximately 50,000. This will be referred to asAdditive 7.

Synthesis Example 8

116.1 g dimethylamine (50%), 87.7 g of 25 wt % aqueous ammonia and 354.3g water were introduced into a reaction vessel equipped with a stirrer,reflux condenser, dropping funnel and thermometer, and after stirring todissolve the ingredients to obtain a homogeneous mixture, 238.6 g ofepichlorohydrin was dripped in using the dropping funnel. After additionwas complete, the mixture was reacted at 80° C. for 15 hours. Next, 2.0g hydrated bisphenol A diglycidyl ether was added from the droppingfunnel, and reacted at 80° C. for 8 hours to obtain a yellow liquefiedaqueous solution containing 40% solids. The weight average molecularweight of the polymer obtained as found by high performance liquidchromatography was approximately 100,000. This will be referred to asAdditive 8.

Comparative Synthesis Example 1

202.9 g dimethylamine (50%), 17.6 g of 24 wt % aqueous ammonia and 310 gwater were introduced into a reaction vessel equipped with a stirrer,reflux condenser, dropping funnel and thermometer, and after stirring todissolve the ingredients to obtain a homogeneous mixture, 238.6 g ofepichlorohydrin was dripped in using the dropping funnel. After additionwas complete, the mixture was reacted at 70° C. for 20 hours to obtain ayellow liquefied aqueous solution containing 45% solids. The weightaverage molecular weight of the polymer obtained as found by highperformance liquid, chromatography was approximately 20,000. This willbe referred to as Additive 9.

Comparative Synthesis Example 2

232.2 g dimethylamine (50%) and 317.4 g water were introduced into areaction vessel equipped with a stirrer, reflux condenser, droppingfunnel and thermometer, and after stirring to dissolve the ingredientsto obtain a homogeneous mixture, 238.6 g of epichlorohydrin was drippedin using the dropping funnel. After addition was complete, the mixturewas reacted at 80° C. for 15 hours to obtain a yellow liquefied aqueoussolution containing 45% solids. The weight average molecular weight ofthe polymer obtained as found by high performance liquid chromatographywas approximately 40,000. This will be referred to as Additive 10.

Comparative Synthesis Example 3

500.0 g monoallylamine hydrochloride (60%) and 1.5 g2,2-azobis-(2-amidinopropane) dihydrochoride were introduced into areaction vessel equipped with a stirrer, reflux condenser, droppingfunnel and thermometer, and the mixture was reacted at 70° C. for 15hours to obtain a 2,2-azobis-(2-amidinopropane) crosslinked compound ofa monoallylamine polymer. Next, the product was diluted with 165.2 gwater to obtain a yellow liquefied aqueous solution containing 45%solids. The weight average molecular weight of the polymer obtained asfound by high performance liquid chromatography was approximately18,000. This will be referred to as Additive 11.

Comparative Synthesis Example 4

700.0 g dicyandiamide (DCDA), 600.0 g diethylenetriamine (DETA), 400.0 gwater and 100 g ammonium chloride (NH₄Cl) were introduced into areaction vessel equipped with a stirrer, reflux condenser, droppingfunnel and thermometer, and the mixture was reacted at 140° C. for 4hours. Ammonia was violently emitted during the reaction. When emissionof ammonia had subsided, heating was stopped, 600 g water was added, and270 g hydrochloric acid was added to neutralize the reaction productgiving a yellow liquefied aqueous solution containing 47% solids. Theweight average molecular weight of the polymer obtained as found by highperformance liquid chromatography was approximately 10,000. This will bereferred to as Additive 12.

Application to Inkjet Recording Medium

Manufacture of Substrate of Inkjet Recording Medium

12 parts of kaolin as a filler, 0.1 parts of rosin sizing agent(commercial name: Sizepin NT-76: Arakawa Chemical Co.) and 0.3 parts ofaluminum sulfate, 0.3 parts of cationized starch and 0.01 parts of yieldenhancing agent (commercial name: Pearl Flock FR-C (Seiko ChemicalIndustries) were mixed with. 100 parts of a pulp slurry comprisingbroadleaf tree bleached pulp (filtered water degree 350 mlcsf) toprepare pulp slurry. Paper was manufactured from the pulp slurryobtained by a twin wire paper making machine, dried and machine calendarfinished to give a raw paper of weighting 72 g/m².

Example 1

Additive 1 synthesized in Synthesis Example 1 was coated on thesubstrate prepared as described above and dried in a size press to 0.8g/m² as dry solids, and calendar finishing was performed to manufacturethe inkjet recording medium of Example 1. In the coating, water wasadded to adjust the resin concentration so as to suitably adjust theadhesion amount on the substrate.

Examples 2-8 and Comparative Examples 1-4

An inkjet recording medium was manufactured exactly as described inExample 1, except that Additives 2-8 synthesized in Synthesis Examples2-8 and Additives 9-12 manufactured in Comparative Synthesis Examples1-4, were used instead of Additive 1 used in Example 1.

Comparative Example 5

An inkjet recording medium was manufactured exactly as described inExample 1, except that water was used for coating instead of Additive 1used in Example 1.

Tests

Transmittance Measurement

Regarding the additives synthesized in Synthesis Examples 1-8 andComparative Shnthesis Examples 1-4, the degree of mutual interactionbetween the ink (commercial name: Scitex 1007, Scitex black ink; Scitex1011, Scitex red ink; Scitex 1012, Scitex blue ink; BC 121, Canon colorprinter ink) and the additive was evaluated by measuring thetransmittance using a Shimadzu Autospectrophotometer UV3100PC(measurement wavelength: 300-800 nm, slit width: 2 nm, samplinginterval: 0.5 nm). 5 μl of ink was dripped into 0.5 ml of additivesolution adjusted to 0.5% concentration, and after shaking the mixturewell, it was left standing overnight. Next, it was filtered through afilter of 0.2 μm pore size, and the transmittance of the filtrate wasmeasured. If the substance obtained by mutual interaction of theadditive and dye is highly insoluble, it precipitates and is filteredoff. It may therefore be determined that the water resistance of therecording medium containing the additive will be higher, the higher thetransmittance of the filtrate. These results are shown in Table 1.

Inkjet Recording Suitability Test

The inkjet recording media prepared in Examples 1-8 and ComparativeExamples 1-5 were used to record images using a multicolor inkjetprinter (commercial name: BJC-400J, Canon) and a monochrome inkjetprinting system (commercial name: 6420J, SciTex Japan), and the resultsevaluated by the following methods are shown in Table 2.

(Image Water Resistance)

30 seconds after recording with the printer, the image was immersed indeionized water at 20° C. for 30 seconds, and after allowing to standand drying, the degree of blurring was visually evaluated. In the testresults, ⊚ indicates a good result with no blurring, ◯ indicates thatsome blurring was observed but was practically insufficient to cause aproblem, Δ indicates that blurring was obserbed and sufficient to causea problem, and x indicates a poor result with much blurring.

Resolution

Fine lines were recorded with the printer, and visually evaluated. Inthe test results, ⊚ indicates a good result with little blurring andnarrow lines, ◯ indicates slight blurring and slightly wider lines butpractically insufficient to cause a problem, Δ indicates blurring andwider lines sufficient to cause a problem, and x indicates a poor resultwith blurring and wide lines.

TABLE 1 Transmissometry result Mole ratio secondary amine/ ammonia/Transmittance epichlorohydrin/ BC 121 Additive crosslinking agent 10071011 1012 (black) Note Synthesis 1:0.11:1.14:0.0002 97% 93% 92% 99%Example1 (Additive1) Synthesis 1:0.11:1.14:0.0003 97% 94% 95% 99%Example2 (Additive2) Synthesis 1:0.11:1.14:0.0003 96% 93% 95% 96%Example3 (Additive3) Synthesis 1:0.11:1.14:0.0003 96% 90% 94% 96%Example4 (Additive4) Synthesis 1:0.11:1.11:0.0007 97% 93% 94% 99%Example5 (Additive5) Synthesis 1:0.25:1.25:0.0008 95% 90% 94% 99%Example6 (Additive6) Synthesis 1:0.25:1.25:0.001 95% 90% 93% 98%Example7 (Additive7) Synthesis 1:1:2:0.003 92% 90% 90% 98% Example8(Additive8) Comparative 1:0.11:1.14:0 90% 18% 51% 33% Synthesis Example1(Additive9) Comparative 1:0:1:0 95% 18% 68% 80% Synthesis Example2(Additive10) Comparative — 80% 20% 40% 20% *1 Synthesis Example3(Additive11) Comparative — 34%  6%  3% 16% *2 Synthesis Example4(Additive12) *1: 2-2-azobis-(2-amidino propane) crosslinked substancefrom monoallylamine polymer *2: mole ratio: DCDA:DETA:NH₄Cl = 1:0.7:0.22

TABLE 2 Ink jet recording aptitude evaluation Image durabilityResolution Example 1 ⊚ ⊚ Example 2 ⊚ ⊚ Example 3 ⊚ ⊚ Example 4 ⊚ ⊚Example 5 ⊚ ⊚ Example 6 ∘ ⊚ Example 7 ∘ ⊚ Example 8 ∘ ∘ Comparative Δ ∘Example 1 Comparative Δ ∘ Example 2 Comparative x ∘ Example 3Comparative x Δ Example 4 Comparative x ∘ Example 5

According to this invention, by incorporating an additive having acationic resin as principal component, this resin being obtained by thereaction of a secondary amine, ammonia, an epihalohydrin and acrosslinking agent as required components, in the surface and/orinterior of a substrate of a recording medium; an inkjet recorded imagewhich has water resistance, little blurring and high resolution, can beobtained.

Industrial Field of Application

By using the additive of this invention, a recording medium suitable formulticolour recording by the ink-jet recording method, giving littleshift in hue, high resolution and excellent image reproducibilityincluding color reproducibility can be obtained. Further, the additiveof this invention prevents fading of dyed yarn or cloth whenwater-soluble dyes are used.

1. An inkjet recording medium, obtained by coating an additive on thesurface of a substrate or introducing the additive to the interior ofthe substrate, wherein the additive comprises a cationic resin as aprincipal component, which resin is obtained by the reaction of at leasta secondary amine, ammonia, an epihalohydrin and a crosslinking agentcomprising at least one compound with two or more aldehyde groups, epoxygroups or isocyanate groups, said resin having a cross-linked structure.2. The inkjet recording medium as defined in claim 1, wherein (liesubstrate is a coated paper comprising a recording layer suitable forrecording by a water-based ink on the substrate surface.
 3. The inkjetrecording medium as defined in claim 2 wherein the coated paper isimpregnated by a solution containing the additive having the cationicresin as a principal component.
 4. The inkjet recording medium asdefined in claim 2, wherein the coated paper is manufactured from a pulpslurry containing the additive having the cationic resin as a principalcomponent.
 5. An ink jet recording medium as defined in claim 1, whereinthe weight average molecular weight of the cationic resin obtained is10,000-500,000.
 6. An inkjet recording medium as defined in claim 1,wherein the ratio of secondary amine: ammonia: epihalohydrin:crosslinking agent to prepare the cationic resin is 1: (0.01-2):(0.5-2.5): (0.00005-0.5).
 7. An ink jet recording medium as defined inclaim 1, wherein the crosslinking agent comprises at least onemultifunctional epoxy compound.
 8. An inkjet recording medium as definedin claim 1 wherein the secondary amine is a dialkylamine, adimethylamine, a diethylamine, or an ethyl monomethylamine.
 9. An inkjetrecording medium as defined in claim 1, wherein the epihalohydrin isepichorohydrin, epiiodohydrin, or epibromohydrin.
 10. An inkjetrecording medium according to claim 1, wherein the substrate is a sleetsubstrate.
 11. The inkjet recording medium as defined in claim 1,wherein the substrate is paper.
 12. The inkjet recording medium asdefined in claim 11, wherein the paper is impregnated by a solutioncontaining the additive having the cationic resin as a principalcomponent.
 13. The inkjet recording medium as defined in claim 11,wherein the paper is manufactured from a pulp slurry containing theadditive having the cationic resin as a principal component.
 14. Aninkjet recording medium as defined in claim 1, wherein the ratio ofsecondary amine: ammonia: epihalohydrin: crosslinking agent to preparethe cationic resin is 1: (0.02-1): (0.8-2.2): (0.0001-0.01).
 15. Aninkjet recording medium according to claim 1, wherein the resin isobtained by mixing a secondary amine and ammonia together, followed bythe addition of an epihalohydrin and a cross-linking agent.
 16. Aninkjet recording, medium according to claim 1, wherein the additiveconsists essentially of a cationic resin.
 17. An inkjet recording mediumaccording to claim 1, wherein the additive consists of a cationic resin.18. An inkjet recording medium, obtained by coating an additive on thesurface of a substrate or introducing the additive to the interior ofthe substrate, wherein the additive comprises a cationic resin as aprincipal component, which resin is obtained by the reaction of at leasta secondary amine, ammonia, an epihalohydrin and a crosslinking agentcomprising polyethylene glycol diglycidyl ether, polypropylene glycoldiglycidyl ether, polytetramethylene glycol diglycidyl ether,polybutadienie diglycidyl ether, resorcinol diglycidyl ether,neopentylglycol diglycidyl ether, 1,6-hexanediol diglycidyl ether,bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol Apolyethylene glycol diglycidyl ether, bisphenol A polypropyleneglycoldiglycidyl ether, hydrated bisphenol A diglycidyl ether, hydroquinonediglycidyl ether, terephthalic acid diglycidyl ether, sorbitolpolyglycidyl ether, polyglycerol polyglycidyl ether,pentaerythritolpolyglycidyl ether, diglyceroylpolyglycidyl ether,glycerolpolyglycidyl ether, or trimethylolpropane polyglycidyl ether,said resin having a cross-linked structure.
 19. An inkjet recordingmedium as defined in claim 18, wherein the ratio of secondary amine:ammonia: epihalohydrin: crosslinking agent to prepare the cationic resinis 1: (0.02-1): (0.8-2.2): (0.0001-0.01).
 20. An inkjet recording mediumaccording to claim 18, wherein the resin is obtained by mixing asecondary amine and ammonia together, followed by the addition of anepihalohydrin and a cross-linking agent.
 21. An inkjet recording mediumaccording to Claim 18, wherein the additive consists essentially of acationic resin.
 22. An inkjet recording medium according to claim 18,wherein the addictive consists of a cationic resin.